The invention relates to a method for operating a mechatronic chassis device of a motor vehicle.
It is assumed that a mechatronic suspension device which allows setting a toe angle of a wheel and a camber angle of the same wheel includes two servomotors. However, each of these servomotors are configured as part of an associated device to not only set one of the angles; instead, each servomotor alone should, when activated, simultaneously change the toe angle of the wheel and the camber angle of the wheel.
A chassis device with the aforementioned properties is disclosed, for example, in WO 2009/052914 A1. The chassis device described therein allows setting the toe angle and camber angle in a particularly simple manner without introducing undue mechanical complexity. The wheel suspension for motor vehicles from WO 2009/052914 A1 is illustrated in the FIGS. 1 and 2 of the present application. The wheel carrier 3 has a wheel-side supporting member 17 on which a vehicle wheel 1 is rotatably mounted. The wheel carrier further includes an axle-side supporting element 19. The two support elements 17 and 19 are interconnected by an actuator 21. This interconnected actuator 21 includes a wheel-side rotary member 23, which is connected to the supporting element 17 and an axle-side rotary member 25, which is connected to the support element 19. Each rotary member 23, 25 is able to rotate about an axis 27, 28 (FIG. 2). The rotation takes place with the aid of servomotors 38 and 39. When rotating by a rotation angle α, the rotary member 23 moves with a tumbling motion about the rotation axis 27. Simultaneously or with a time offset, the rotary member 25 can be rotated by a rotation angle β relative to the support element 19. When rotating the two rotary members 23, 25, the wheel-side rotary member 23 is deflected by a pivot angle φ relative to the axle-side rotary member 25. A desired toe angle δ and a desired camber angle ε of the wheel 1 can be set by suitably adjusting the rotation angles α and β of the respective rotary members 23, 25.
It will be assumed that the servomotors are controlled in a predetermined manner, see the connections 51 for a control unit 53. The control unit 53 processes target values relating to the toe angle δ and the camber angle ε; to implement the target values, the servomotors are then driven in a predetermined manner, as disclosed in WO 2009/052914 A1.
However, there is a risk that one of the servomotors cannot be operated, either because it has an inherent failure, or because the connection 51 to the control unit 53 is inoperative.
Since the failure of these components cannot be predicted or controlled, it may happen that a certain toe angle and a certain camber angle are set at a certain time of a failure, which should not to remain permanently set. On the other hand, not every desired track angle in combination with any desired camber angle can be set with the remaining operative servomotor alone.